Multifunctional ZnO-Co3O4 @ polymer hybrid nanocoatings with controlled adsorption,photocatalytic and anti-microbial functions for polluted water systems

Environmental Science and Pollution Research - Triple action pollutant responsive multi-layer hybrid nanocoatings of architecture PEI(PAA/ZnO-Co3O4)n were constructed through ZnO-Co3O4 binary oxide...     

Polyelectrolyte enhanced ultrafiltration (PEUF) for the removal of Cd(II): effects of organic ligands and solution pH

This study focused on the effects of pH and organic ligands, namely ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), and citric acids, on the removal and recovery of Cd(II) in polyelectrolyte enhanced ultrafiltration (PEUF). Polyethylenimine (PEI), which can bind with both positively charged metal ions by coordination bonding and negatively charged ligand-metal complexes by charge attraction, was employed as a chelating polymer. The removal and recovery of Cd species was greatly dependent on the chemistry of organic ligands according to solution pH, particularly being related to the distribution of Cd-ligand complexes at different pH levels. In the presence of EDTA, the dominant Cd species are negatively charged Cd(EDTA)(2-) and CdH(EDTA)(-) over the range of pH levels investigated, interacting with PEI via electrostatic attraction and being less pH dependent. On the other hand, the pH effects of both NTA and citric acid systems are similar to that for the system without organic ligands. This was associated with the fact that free Cd ions were predominant at the acidic pH range in both NTA and citric acid systems.     

Selective separation of copper(II) and nickel(II) from aqueous media using the complexation-ultrafiltration process

The polyethylenimine (PEI) as complexing agent was used to study the complexation-ultrafiltration (CP-UF) process in the selective removal of Cu(II) from Ni(II) contained in aqueous media. Preliminary tests showed that optimal chemical conditions for Cu(II) and Ni(II) complexation by the PEI polymer were pH>6.0 and 8.0, respectively, and polymer/metal weight ratio of 3.0 and 6.0, respectively. The effect of some important operating parameters on process selectivity was studied by performing UF tests at different parameters: pH, polymer/metal weight ratio, transmembrane pressure (TMP), and membrane cut-off in a batch experimental set-up. It was observed that process selectivity was achieved by choosing the pH value for obtaining a preferential copper complexation (pH 6.0), and the polymer/metal ratio needed to bound only the copper ion (3.0). The selective separation by UF tests was performed by using both a laboratory aqueous solution and a real aqueous effluent (water from Emoli torrent, Rende (CS)). The Iris 30 membrane at TMP of 200 kPa (2 bar) for both aqueous media gave the best results. A complete nickel recovery was reached, and copper recovery was the highest for this membrane (94% and 92%). Besides at this pressure, a lower water amount was needed to obtain total nickel recovery by diafiltration. A little higher membrane fouling was obtained by using the river effluent due to the presence of dissolved organic and inorganic matter.     

Partitioning of polychlorinated biphenyls in octanol/water, triolein/water, and membrane/water systems

The use of the octanol/water partition constant (Kow) as a surrogate parameter for lipid/water partitioning of persistent organic pollutants (POPs) was reassessed by comparing the measured Kow of 12 selected polychlorinated biphenyl congeners (PCBs) with partition constants in triolein/water (Ktw) and membrane/water (Kmw) systems. Kow and Ktw were measured by the slow-stirring method. Kmw was measured by an adaptation of the slow-stirring method using suspensions of phosphatidylcholine and phosphatidylserine liposomes. Partitioning of POPs to octanol, triolein, and liposomes is similar but not equal. The log-log correlation for Kow and Ktw is excellent (r2 = 0.982) and that for Kow and Kmw is somewhat weaker (r2 = 0.856). Ktw values are greater than Kow by a factor of 1.6. Kmw of some PCB congeners exceed both Kow and Ktw by an order of magnitude. The differences are attributed to different PCB activity coefficients in the different lipid phases. The results imply that Kow can be used as a reasonable conservative estimate of lipid/water partitioning. But the observed differences between Kow and Kmw also indicate that using Kow to predict accumulation of POPs, particularly highly hydrophobic ones, in the polar lipids of organisms will underestimate their concentrations at equilibrium.     

Decomposition of dihaloacetonitriles in water solutions and fortified drinking water samples

An investigation of the decomposition of dihaloacetonitriles (DHANs) in water solutions and fortified drinking water samples was conducted. The concentrations of dichloroacetonitrile (CHCl2CN, DCAN), bromochloroacetonitrile (CHBrClCN, BCAN) and dibromoacetonitrile (CHBr2CN, DBAN) were determined by a gas chromatography mass spectrometry (GC-MS) method at regular time intervals and different temperatures. The effect of sodium thiosulfate (Na2S2O3), which is used as a preservative in water samples, was also examined. The rates of decomposition were determined for each compound. The results show that the reactions are faster in fortified drinking water samples than in ultrapure water solutions. They are also favored at higher temperature, especially when sodium thiosulfate is present. The highest decomposition rate is shown by DCAN, followed by BCAN and DBAN, while at the presence of sodium thiosulfate the decomposition of DBAN is the fastest.     

净水厂生产废水回用对供水水质的影响

通过研究生产废水回用对水质的影响,认为生产废水含固率是影响回用效果的重要评价指标,回用澄清池排泥水和滤池反冲洗水,对水质的影响规律相似.改善混凝条件的最佳含固率范围也是回用对水质影响最小的含固率范围.当含固率小于1%时,回用不会对水质造成影响,当含固率大于1%时,回用较无回用时的水质变差,但不会超过水质标准.回用生产废水可以提高有机物的去除率,主要是因为生产废水中含有的Al(OH)3沉淀物的物理吸附和卷扫絮凝功能.     

电子去离子净水技术

概述了EDI净水技术的发展历程、原理、组件型式与性能     

Perfluorochemicals in water reuse

Faced with freshwater shortages, water authorities are increasingly utilizing wastewater reclamation to augment supplies. However, concerns over emerging trace contaminants that persist through wastewater treatment need to be addressed to evaluate potential risks. In the present study, perfluorinated surfactant residues were characterized in recycled water from four California wastewater treatment plants that employ tertiary treatment and one that treats primary sewage in a wetland constructed for both treatment and wildlife habitat. Effluent concentrations were compared with surface and groundwater from a creek where recycled water was evaluated as a potential means to augment flow (Upper Silver and Coyote Creeks, San Jose, CA). In the recycled water, 90-470 ng/l perfluorochemicals were detected, predominantly perfluorooctanoate (PFOA; 10-190 ng/l) and perfluorooctanesulfonate (PFOS; 20-190 ng/l). No significant removal of perfluorochemicals was observed in the wetland (total concentration ranged 100-170ng/l across various treatment stages); in this case, 2-(N-ethylperfluorooctanesulfonamido) acetic acid (N-EtFOSAA), perfluorodecanesulfonate (PFDS), and PFOS were dominant. Though there is currently no wastewater discharge into the creeks, perfluorochemicals were found in the surface water and underlying groundwater at a total of 20-150 ng/l with PFOS and PFOA again making the largest contribution. With respect to ecotoxicological effects, perfluorochemical release via recycled water into sensitive ecosystems requires evaluation.     

Photodegradation of phosphonates in water

Phosphonates are widely used as chelating agents, e.g., in water cooling systems, in bleaching baths or as scale inhibitors in deflocculation agents. They are considered to be difficult to degrade and produce aminomethylphosphonic acid (AMPA) as a metabolite. As the fate of phosphonates in the environment is not very well known the present work aims at simulating the time dependent photodegradation of four selected phosphonates: nitrilotris-methylenephosphonic acid (NTMP), ethylenediamine-tetra-methylenephosphonic acid (EDTMP), diethylenetriaminepenta-methylenephosphonic acid (DTPMP) and hexaethylenediamine-tetra-methylenephosphonic acid (HDTMP), at concentrations of 1 mg/l (i.e. 3.2 microM NTMP, 2.3 microM EDTMP, 1.7 microM DTPMP and 2.0 microM HDTMP) irradiated by a middle pressure mercury lamp emitting between 190 and 600 nm. The influence of iron under different pH ranges (3, 5-6 and 10) are tested. The degradation of phosphonates is measured by the release of orthophosphates (PO4-P) and aminomethylphosphonic acid (AMPA). This study shows that phosphonates are substances that undergo UV light conversion, which is enhanced in the presence of iron. The half-life without iron is between 15 and 35 min at pH 3, between 10 and 35 min at pH 5-6 and between 50 and 75 min at pH 10. The half-life in the presence of 3.6 microM iron is between 5 and 10 min at pH 3, between 5 and 15 min at pH 5-6 and between 35 and 60 min at pH 10. The individual substances do not significantly influence the reaction rates whereas the presence of iron and the pH have significant effects. The total conversion of phosphonates after 90 min is 75-100% for pH values of 3 and 5-6 and 55-75% for a pH of 10 dependent on the presence of iron. In the environment longer degradation times are to be expected since natural light is weaker by a factor between 125 and 300 in the UVB, a factor between 3 and 8 in the UVA and of the same intensity in the visible range than the light in our study. Although orthophosphates are the major products, AMPA is also shown to be a by-product of the photodegradation of phosphonates that is later converted into orthophosphate.     

Bromide affecting drinking water mutagenicity

The effect of bromide on the mutagenicity of artificially recharged groundwater and purified artificially recharged groundwater after chlorine, ozone, hydrogen peroxide, permanganate, and UV treatments alone and in various combinations was studied. The highest mutagenicity was observed after chlorination, while hydrogen peroxide-ozone-chlorine treatment produced the lowest value for both waters. Chlorinated waters, which were spiked with bromide, had up to 3.7 times more mutagenic activity than waters without bromide after every preoxidation method. 3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) was found to correspond as much as 76% of the overall mutagenicity in the waters not spiked with bromide. MX formation was found to be lower when the treated water contained bromide, implicating the formation of brominated MX analogues. Trihalomethane formation increased when the treated water contained bromide.     

Is pesticide sorption by constructed wetland sediments governed by water level and water dynamics?

Constructed wetlands (CWs) are used to reduce the pesticide inputs from tile drainage or run-off to surface water. Their effectiveness appears variable and remains to be better characterized and understood. The aim of this study was to assess the influences of two hydraulic parameters (i.e., dynamics and water level) on the sorption process occurring in CWs. Then, two solid/liquid ratios were studied (1/1 and 1/5) to mimic the water level variation in the field, and two agitation speeds were used (none and gentle agitation) to simulate different water dynamics (stagnation and flow pass, respectively). Sorption kinetics and isotherms were obtained for four pesticides with contrasting properties. The pesticide adsorption coefficients were classified as follows: boscalid (BSC) > cyproconazole (CYP) > isoproturon (IPU) ～ dimethachlor (DMT) at any ratio or agitation, in agreement with their water solubilities and K _ow values. The effect of the solid/liquid ratio was evidenced for all conditions. Indeed, the adsorption equilibrium time was reached more quickly for the 1/1 ratio (24–72 h) than for the 1/5 ratio (96–120 h). In addition, the adsorption coefficients (K _f ^ads) were larger for the 1/1 ratio (1.8–11.2 L kg^?1) than for the 1/5 ratio (1.0–5.9 L kg^?1). The agitation effect was ?more evidenced for the 1/5 ratio and for the more hydrophobic molecules, such as BSC and CYP, for which adsorption equilibrium time was never reached with agitation (>120 h), while it was reached at 96 h without agitation. Moreover, the K _f ^ads values were larger with agitation than without agitation for BSC and CYP, whereas they were similar for the two agitations for IPU and DMT. Our results demonstrated that the hydrodynamic function of CWs could influence pesticide sorption with variable effects according to the molecular properties and consequently influence the mitigation effect of CWs throughout the year.     

Remediating dicamba-contaminated water with zerovalent iron

Dicamba (3,6-dichloro-2-methoxybenzoicacid) is a highly mobile pre- and post-emergence herbicide that has been detected in ground water. We determined the potential of zerovalent iron (Fe0) to remediate water contaminated with dicamba and its common biological degradation product, 3,6-dichlorosalicylic acid (DCSA). Mixing an aqueous solution of 100 microM dicamba with 1.5% Fe0 (w/v) resulted in 80% loss of dicamba within 12 h. Solvent extraction of the Fe0 revealed that dicamba removal was primarily through adsorption; however when the Fe0 was augmented with Al or Fe(III) salts, dicamba was dechlorinated to an unidentified degradation product. In contrast to dicamba, Fe0 treatment of DCSA resulted in removal with some dechlorination observed. When DCSA was treated with Fe0 plus Al or Fe(III) salts, destruction was 100%. Extracts of this Fe0 treatment contained the same HPLC degradation peak observed with the Fe0 + Al or Fe(III) salt treatment of dicamba. Molecular modeling suggests that differences in removal and dechlorination rates between dicamba and DCSA may be related to the type of coordination complex formed on the iron surface. Experiments with 14C-labeled dicamba confirmed that Fe-adsorbed dicamba residues are available for subsequent biological mineralization (11% after 125 d). These results indicate that Fe0 could be potentially used to treat dicamba and DCSA-contaminated water.     

强化混凝工艺深度处理给水厂排泥废水

水厂废水的综合处理与回用是我国供水行业的新趋势和节水目标所在,采用强化混凝技术进行水厂排泥废水的深度处理。通过混凝剂筛选实验和有机物表征确定最佳混凝剂为高效聚合铝(HPAC),适宜投加量为650 mg/L。当混凝剂HPAC投加量为650 mg/L时,对COD、TOC、浊度和色度的去除率分别为82.5%、89.8%、95%和92.5%,相应的出水值分别为58 mg/L、8.46 mg/L、2.35 NTU、13度,COD满足《污水综合排放标准》(GB 8978-1996)的要求(COD≤100 mg/L),同时实验结果显示聚合氯化铝(PAC)、HPAC、三氯化铁(FeCl3)主要去除分子量处于>1 300 Da范围的有机物,对分子量处于744～1 300 Da之间的有机物去除有限。     

四种净水工艺对水源水微量有机物去除的研究

以UV254和CODMn代表饮用水源水中有机物替代指标.对常规处理、生物陶粒预处理、生物滤池、生物活性炭(BAC)、颗粒活性炭(GAC)、纳滤和光催化氧化进行组合,形成不同的处理流程,研究各流程对UV254和CODMn的去除效果.结果表明,各工艺流程都有一定的处理效率,其中以生物滤池和纳滤为主的组合流程处理效果最佳.此流程对UV254的去除率接近100%,CODMn的去除率达到78.6%,大大提高了饮用水的安全性.     

Occurrence of perfluorooctanoate and perfluorooctanesulfonate in the Korean water system: implication to water intake exposure

Perfluorinated compounds (PFCs) measured in surface running waters indicated the existence of different emission sources in eight main city basins. The tap water reflected the contamination pattern and levels in their corresponding source water basins. The daily intakes through tap water consumption ranged from <0.01 to 0.73 ng kg⁻¹ d⁻¹ for perfluorooctanoate (PFOA) and <0.01 to 0.08 ng kg⁻¹ d⁻¹ for perfluorooctanesulfonate (PFOS). Tap water intake-derived exposure accounted for 8.6%-101% (for PFOA) and while <10% (for PFOS) of total daily exposure, which was estimated from Korean serum concentrations using a pharmacokinetic model. Our findings indicate that tap water intake could be an important contributor to PFOA exposure in Korean populations; accordingly, additional efforts are necessary to improve the removal efficiency of perfluorinated compounds (PFCs) in the water purification process. However, more fundamentally the aim would be to reduce the discharge of PFCs from potential sources within the basin.     

Removal of arsenic from water by electrocoagulation

In the present study electrocoagulation (EC) has been evaluated as a treatment technology for arsenite [As(III)] and arsenate [As(V)] removal from water. Laboratory scale experiments were conducted with three electrode materials namely, iron, aluminum and titanium to assess their efficiency. Arsenic removal obtained was highest with iron electrodes. EC was able to bring down aqueous phase arsenic concentration to less than 10 microgl(-1) with iron electrodes. Current density was varied from 0.65 to 1.53 mAcm(-2) and it was observed that higher current density achieved rapid arsenic removal. Experimental results at different current densities indicated that arsenic removal was normalized with respect to total charge passed and therefore charge density has been used to compare the results. Effect of pH on arsenic removal was not significant in the pH range 6-8. Comparative evaluation of As(III) and As(V) removal by chemical coagulation (with ferric chloride) and electrocoagulation has been done. The comparison revealed that EC has better removal efficiency for As(III), whereas As(V) removal by both processes was nearly same. The removal mechanism of As(III) by EC seems to be oxidation of As(III) to As(V) and subsequent removal by adsorption/complexation with metal hydroxides generated in the process.     

Organic contaminates in water

Abstract

The carbon adsorption method was used for separating organic matter from large samples of drainage, river and tap water. The carbon chloroform extract (CCE) was separated into different solubility fractions and the neutral fraction was separated into aliphatic, aromatic and oxy‐compounds using column chromatography. The aromatic fraction was subjected to TLC, IR and UV analysis. The pesticide endrin was present in both river and tap water at concentrations of 0.7 and 1.5 ppb, respectively.     

低动力复合净水系统净化生态农庄景观池水质

采用生物填料、阿科蔓生态基和生态浮盆等材料构建低动力复合净水系统(LCWPS)进行生态农庄人工景观池水质净化技术示范研究。系统稳定运行后的周年监测结果表明,整体系统使人工景观池的CODMn、TN、NH4+-N、TP和浊度分别下降61.1%～62.8%、36.0%～39.9%、14.3%～35.7%、66.7%～79.5%和76.8%～79.8%,水质溶解氧浓度(DO)上升72.7%～126.0%,景观池水质达到《地表水环境质量标准》(GB3838-2002)中景观水域需要的V类水质标准,并能长期保持稳定。从管理维护成本角度考虑,利用LCWPS净化生态农庄人工景观池水质能达到节能节水的目的。     

Behavior of fenhexamid in soil and water

A study was conducted to investigate fenhexamid (FEX) behavior in soil and in water. FEX proved to be rather stable at acid pH but showed slight degradation at neutral and alkaline pH. After 101 days of FEX spiking of a soil sample, 94% at pH 4, 12% at pH 7 and 23% at pH 9 of the active ingredient was still present. In natural water the rate of FEX disappearance appeared to be slow which may be due to abiotic rather than biotic processes. The soil degradation tests showed low persistence of the active ingredient if a good microflora activity is guaranteed (DT(50) about 1 day). Moreover, in absence of microorganisms, FEX proved to be stable. Humidities of 25 and 50% of Water Holding Capacity (WHC) influenced in equal measure the rate of degradation. From the same soil, a bacterium was isolated and identified as Bacillus megaterium, which was able to metabolize FEX with the hydroxylation of the cyclohexane ring. Moreover, FEX showed an elevated affinity for humic acid (73%), smectite (31%), and ferrihydrite(20%) and low affinity for vermiculite (11%) and kaolinite (7%).     

Pesticide residues in thermal mineral water in Greece

Eight different hot springs (SPA) in Greece were monitored over a one-year survey for priority pesticide residues. A specific and effective procedure including solid phase extraction in combination with HPLC and GC analytical methods were applied. Samples that were sensitive to nitrogen-phosphorus (NPD) and/or electron capture (ECD) detectors were analysed by capillary gas chromatography. From the twenty-six water samples, pesticide residues were detected in fourteen of them (54%) but no one exceeding the European Union Maximum Acceptable Concentration (MAC). Lindane (gamma-BHC) was the most frequently detected pesticide. It was found in nine samples (35%) in concentrations from < 0.005 to 0.01 microg/L. Other pesticides detected were phorate (in five samples), propachlor (in two samples) and chlorpyriphos ethyl (in three samples) but in concentrations far below the permissible levels.